Let the user pass the framework image to use

Let's keep things simple for now. Trying to figure out the right
framework image automatically will be very error prone. By making it a
manual setting, we allow the user to even set it to a custom image or
use one that they know it works.

Signed-off-by: Dimitris Karakasilis <dimitris@karakasilis.me>

cmd/dockerfile.go

@@ -25,10 +25,22 @@ func NewDockerfileCmd() *cobra.Command {
 			cmd.SilenceUsage = true
 			cmd.SilenceErrors = true // Do not propagate errors down the line, we control them
 
-			rootfsDir, _ := cmd.Flags().GetString("rootfs-dir")
-			baseImageURI, _ := cmd.Flags().GetString("base-image-uri")
+			rootfsDir, err := cmd.Flags().GetString("rootfs-dir")
+			if err != nil {
+				return err
+			}
 
-			a := action.NewDockerfileAction(rootfsDir, baseImageURI)
+			baseImageURI, err := cmd.Flags().GetString("base-image-uri")
+			if err != nil {
+				return err
+			}
+
+			frameworkImage, err := cmd.Flags().GetString("framework-image")
+			if err != nil {
+				return err
+			}
+
+			a := action.NewDockerfileAction(rootfsDir, baseImageURI, frameworkImage)
 			dockerfile, err := a.Run()
 			if err != nil {
 				return err
@@ -48,4 +60,5 @@ func init() {
 	rootCmd.AddCommand(c)
 	c.Flags().StringP("rootfs-dir", "r", "", "the directory containing the extracted base image rootfs")
 	c.Flags().StringP("base-image-uri", "i", "", "the URI of the base image")
+	c.Flags().StringP("framework-image", "i", "", "the URI of the base image")
 }